Heat pump having drain pan heating means



Feb. 12, 1963 5. DE KANTER HEAT PUMP HAVING DRAIN PAN HEATING MEANS Filed June 19, 1961 Fl 6. l

F'IG.2

INVENTOR. SCIPIO do KANTER lax $1M H l S ATTORNEY tits The present invention relates to a heat pump and more particularly to an arrangement for assuring proper drainage of condensate water or frost which collects on the outdoor heat exchanger of' the heat pump during operation of the pump onthe heating cycle and for preventing accumulation of frost and ice on the components adjacent the outdoor heat exchanger duringoperation of the heat pump on'the heating cycle. I

Heat pumps, employed for cooling a dwelling or other structure in. the summer and for heating the structure during the winter, include a reversible refrigeration systern having anindoor heat exchanger, a compressor, and an outdoor heat exchanger all connected in reversible refrigerant flow relationship. Refrigerant expansion means are usually provided for expanding refrigerant from condenser pressure to evaporator pressure during the flow of refrigerant through the system in either direction to provide cooling or heating of the air circulated over the indoor heat exchanger. A large fan or blower circulates outdoor air over the outdoor heat exchanger into which heat is dissipated during the cooling cycle operation and from which heat is absorbed by the refrigerant circulating through the outdoor heat exchanger during the heating cycle operation. As is well understood in the art, the outdoor heat exchanger functions as an evaporator during the heating cycle and operates at a lower temperature than the surrounding air from which heat is being extracted with the result that, under certain climatic conditions, frost accumulates on this heat exchanger. A layer of frost on the outdoor heat exchanger or evaporator reduces the efficiency of the system to such an extent that it is necessary to periodically remove and dispose of this frost accumulation. To accomplish this, it is common practice to raise the temperature of the outdoor heat exchanger above the freezing point of water and to dispose of the melted frost by means including a drain pan having a suitable drain line for carrying water away from the unit. Since the drain pan is normally positioned beneath the outdoor heat exchanger and is normally subjected to the same outdoor temperatures as this heat exchanger, the low outdoor temperatures sometime cause an accumulation of ice in the drain pan with the resulting freezing or plugging of the drain hole leading from the pan.

Furthermore, the air flow through the outdoor unit is usually substantial and, when this air circulates over the drain pan, it sometimes violently agitates the water in the drain pan, causing some of the water to become entrained in the air stream and be deposited on other components in the outdoor unit. This water then freezes on these components and builds up an ice and frost accumulation thereon. It has been found that this ice build up greatly impedes the operation of the components of the outdoor unit. For example, water thrown onto the scroll of the blower or fan sometimes builds up to the extent that it interferes with the normal operation of the blower or fan.

It is, therefore, an object of the present invention to provide an improved arrangement tor preventing the accumulation of frost and ice in the drain pan and on the other components of the outdoor unit of a heat pump.

A more specific object of the present invention is to provide an improved arrangement for preventing water in the drain pan beneath the outdoor heat exchanger refrigerant line. circulating a stream of outdoor air in heat exchange re- .there is employed a heat pump including a reversible refrigeration system including a compressor, an indoor heat exchanger, an outdoor heat exchanger, all connected in reversible refrigerant flow relationship. A refrigerant line connected between the indoor and outdoor heat exchangers is provided with refrigerant expansion means for expanding refrigerant from condenser pressure to evaporator pressure during refrigerant flow through the Air circulating means is provided for lationship over the outdoor heat exchanger. Mounted beneath the outdoor heat exchanger is a drain pan for receiving and draining condensate water and frost which collects on the outdoor heat exchanger during the heating cycle operation of the outdoor heat exchanger. In order to assure disposal of the contents of the drain pan and to melt any solid frost or ice collected therein, a portion of the refrigerant line between the indoor and outdoor refrigerant expansion means is disposed in the drain pan so that warm high pressure refrigerant flowing through this line during operation of the refrigeration system in either direction warms the contents of the drain pan. Attached to the refrigerant line within the drain pan and enclosing the drain pan in the area between the outdoor heat exchanger and the air circulating means is a cover or extended surface means for retaining condensate water within the drain pan during operation of the fan and for confining the heat being dissipated by the refrigerant line to the region beneath the cover.

For a better understanding of the invention referece may be had to the accompanying drawing in which:

FIG. 1 is a diagrammatic illustration of the heat pump installation embodying the present invention; and

FIG. 2 is a sectional view of the drain pan of the heat pump installation of FIG. 1 illustrating the cover arrangement adapted to retain heat and condensate water within the confines of the drain pan.

Referring now to the drawing, the illustrated heat pump comprises a reversible refrigeration system which inclu es an outdoor unit 1 including a compressor 4 and an outdoor heat exchanger 3 connected in reversible refrigerant flow relationship by means of suitable refrigerant tubing with an indoor heat exchanger 2. A reversing valve 5 receives high pressure refrigerant gas from the compressor 4 through the exhaust: tube 24 and directs low pressure suction gas toward the compressor through the suction tube 25. The reversing valve 5 may be controlled to direct the refrigerant from the compressor through the remaining portions of the refrigerating system so that the indoor coil 3 functions either as an evaporator or a condenser while the outdoor heat exchanger 3 functions respectively as a condenser or as an evaporator. During operation of the system on the heating cycle, the reversing valve or switch-over valve 5 directs flow of high pressure refrigerant gas from the compressor 3 into the indoor heat exchanger 2 which then functions as a condenser or as a heating coil to warm the air to be conditioned and to condense the refrigerant gas into liquid form. The refrigerant is partially or completely condensed by the air circulated through the indoor heat exchanger 2 and the refrigerant then flows Q through the refrigerant line generally designated s, toward the outdoor heat exchanger 3.

During operation of the heat pump on the cooling cycle, high cressure refrigerant gas is directed by the reversing valve into the outdoor heat exchanger 3, where the high pressure refrigerant gas is condensed by the air stream circulated over the outdoor heat exchanger by an air moving means or fan '7, which is driven by the motor 3 disposed in the outdoor unit. On the cooling cycle, the refrigerant gas is condensed in the outdoor exchanger 3 and then flows through the refrigerant line 6 toward the indoor heat exchanger 2 where it cools the air being circulated from the enclosure over this heat exchanger.

Means are provided in the refrigerant line 6 for expanding the condensed refrigerant from condenser pressure to evaporator pressure during flow of refrigerant though the refrigerant line 6 in either direction. More specifically, there are provided in the refrigerant line 6 expansion means or valves 9 and it adapted to expand condensed refrigerant flowing toward the heat exchangers 2 and 3 respectively. Thus, during the heating cycle, when the flow of refrigerant is from the indoor heat exchanger 2 toward the outdoor heat exchanger 5, refrig erant flows around the expansion means it through the bypass conduit in and then is expanded to evaporator pressure as it flows through the expansion valve 9 associated with the outdoor heat exchanger 3. A check valve 14 in the bypass conduit 13 prevents flow of refrigerant around the expansion valve h when flow through the line 6 is from the indoor heat exchanger 2 toward the outdoor heat exchanger During the cooling cycle, when refrigerant flow through line 6 is in the opposite direction, refrigerant flows through the bypass conduit 13 and check valve 14 and is then forced to flow through the expansion valve ill by the check valve 12 in the bypass in adjacent the indoor heat exchanger. It will be noted that the refrigerant line 6 always contains hot condensed refrigerant regardless of the direction of refrigerant flow through the refrigeration system and, as will be hereinafter explained, this plays an important part in assuring proper drainage of water from the outdoor unit during the heating season.

During the heating cycle operation of the heat pump, the outdoor heat exchanger 3 operating a temperatures below the outdoor air temperatures, frequently atrains temperatures below freezing with the result that frost accumulates on the surface thereof. Because of the insulating character of this frost layer, it is essential that it be removed periodically in order to maintain the proper operation of the system. For this purpose various heating means have been employed for periodically raising the temperature of the outdoor coils to temperatures at which the frost will be removed from the heat exchanger and collected in a drain pan 13 disposed beneath the outdoor heat exchanger. In the present instance the bottom or base pan of the outdoor unit forms the drain pan 1% and water and frost drops from the heat exchanger 3 into the area in the bottom of the outdoor unit beneath the heat exchanger 3 and collects in this region between the heat exchanger 3 and the partition iii. Electrical heating by means of suitable resistance heaters and hot gas defrosting by means of hot compressed refrigerant from the compressor are both common arrangements for defrosting the outdoor coil or heat exchanger of the heat pump. While the present invention is not restricted to any particular arrangement for defrosting the outdoor heat exchanger 2, it is preferably defrosted by operating the heat exchanger as a condenser, that is, by reversing the How of refrigerant through the system so that, when hot gas from the compressor is fed to the outdoor heat exchanger, it melts the front and ice which has collected thereon.

During defrost operation most of the frost on the outdoor heat exchanger 3 will melt and the resultant liquid flow into tie drain pan l8. However, under relatively low outdoor temperature conditions, the unrnelted frost or ice may or drop from the heat exchanger into the outdoor drain pan 1% where it is no longer in a position to be melted by the refrigerant flowing through the heat exchanger 3. Because the drain pan is also subiected to below freezing outdoor air temperatures, the liquid condensate flowing from the outdoor heat exchanger 3 may freeze before it flows through the drain opening 1'} in the drain pan 1%. The ice accumulation in the drain pan may lead to a freeze up of the drain pan and drain line thereby preventir disposal of the condensate in the present invention, this ice accumulation is avoided by arrang ng a portion of the refrigerant line a, which always carries hot refrigerant ss of the direction of how of refrigerant through the system, within the drain pan 18 to warm or heat the condensate therein. As may be seen in FIG. 1, a (mu volution or turn on of refrigerant line s extends into the drain pan 18 between the partition l7 and the heat exchanger 3. Because the turn 6a is always upstream from the valve that is operating to expand refrigerant from condenser pre are to evaporator pressure, warm or hot n'ant from the heat exchanger operating condensed refr as a condenser always flows through turn 6a regardless of the direction of refrigerant flow through the system and heat i always supplied to the drain pan is regardless of the direction of refrigerant flow through the refrigerant line 6.

In the present invention the heat losses due to the exposure the high pressure line 6a to the outside temperature may be cut down by covering the drain pan 13 with a suitable cover or extended surface 29 in the area between the heat exchanger 3 and the orifice partition 17. in the preferred embodiment of the invention, as may clearly be seen in FIG. 2, the drain pan cover 20 is brazed or soldered to the convolutions of the coil 6a and conducts heat from these coils to the remaining region below the cover The extended surface 2i} is preferably made of a heat conducting material so that heat is quickly conducted thereby to the entire area in the drain pan 13 between heat exchanger 3 and the partition 17. in further explanation of the function of the drain pan cover 2% as set forth above, the heat transferred to the cover 2t? by the coil so also causes ice dropping onto the top of the cover from the heat exchanger 3 to mel and drain off the cover into the lower portion of the drain pan 1% where it is retained in liquid form until it drains through the outlet opening 19.

in the illustrated embodiment of the invention, air enters the outdoor unit 1 in the direction of the arrows shown in PKG. 1 and flows from the outside through the heat exchanger 3 whereupon it is circulated by the fan through the opening 16 in the partition 17 and thence into the other portions of the outdoor unit. It will be noted that air flowing through the outdoor unit 1 first enters the heat exchanger 3 and is then blown by the fan 7 into other portions of the unit thereby creating a low pressure region 21 (seen best in H6. 2) between the fan 7, or partition 1. surrounding the fan, and the outdoor heat exchanger 3 disposed upstream from the fan. it will be understood that the air flowiru through the heat exchanger 3 through the area 21 between the partition 17 and the heat exchanger 3, flows at a substantial velocity and, if permitted to flow over the water in the sump 13 causes violent agition of the water in the sump thereby entraining this water into the air stream. It has been found in the winter that water, collecting on the other components of the outdoor unit and particularly on the orifice partition 17 of the outdoor unit, freezes and builds up after an extended period of use. The build up of frost and ice on the partition 1? becomes so great that, whenever the unit is turned oil and the outdoor fan 17' stops for one reason or another, such as because the enclosure or dwelling has been sufficiently warmed, the

ice sags onto the outdoor fan 7 and freezes the fan solidly into ice build up on the orifice opening 16. Then, when the unit is again started, the fan is prevented from rotating and this is likely to cause damage to the fan motor or other components of the outdoor unit. The cover or extended surface 20 prevents the air flowing through the heat exchanger 3 from agitating the condensate water in the drain pan area, thereby retaining all of the condensate water in the drain pan. This, of course, prevents the water from being thrown or carried by the air stream into the other portions of the unit and thereby eliminates the frost or ice build up on other components in the outdoor unit.

While in accordance with the patent statutes there has been described what at present is considered to be the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, the aim of the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A heat pump comprising a reversible refrigeration system including an indoor heat exchanger, an outdoor heat exchanger, a compressor, a refrigerant line connecting said indoor and said outdoor heat exchangers, a heating cycle refrigerant expansion means in said refrigerant line for expanding refrigerant flowing from said indoor heat exchanger toward said outdoor heat exchanger, a cooling cycle refrigerant expansion means in said refrigerant line for expanding refrigerant flowing from said outdoor heat exchanger toward said indoor heat exchanger, a drain pan associated with said outdoor heat exchanger for collecting condensate water and frost removed from said outdoor heat exchanger, said refrigerant line having at least a portion thereof between said heating and cooling cycle expansion means arranged in heat exchange relationship in said drain pan for warming said drain pan at all times during flow of refrigerant through said refrigerant line, and a cover extending over said drain pan above said refrigerant line for retaining Water collecting within said drain pan, said cover being formed of heat conducting material and in contact with said refrigerant line so that heat dissipated by said refrigerant line is distributed throughout said drain pan.

2. A heat pump comprising a reversible refrigeration system including an indoor heat exchanger, an outdoor heat exchanger, a compressor, a refrigerant line connecting said indoor and said outdoor heat exchangers, a heating cycle refrigerant expansion means in said refrigerant line for expanding refrigerant flowing from said indoor heat exchanger toward said outdoor heat exchanger when said system is operating on a heating cycle, cooling cycle refrierant expansion means in said refrigerant line for expanding refrigerant flowing from said outdoor heat exchanger toward said indoor heat exchanger when said system is operated on a cooling cycle, a drain pan having at least a portion thereof disposed beneath said outdoor heat exchanger for collecting condensate water and frost removed from said outdoor heat exchanger, said refrigerant line having at least a portion thereof between said heating and cooling cycle expansion means arranged in heat exchange relationship in said drain pan for warming said drain pan during flow of refrigerant through said line in either direction, and an extended surface cover of heat conducting material attached to said refrigerant line and extending over said drain pan for retaining water collecting therein and for transferring heat from said refrigerant flowing through said refrigerant line in said drain pan throughout said drain pan.

3. An air conditioner comprising a refrigeration system including a compressor, a condenser and an evaporator connected in refrigerant flow relationship, a refrigerant line connecting said condenser with said evaporator, refrigerant expansion means in said refrigerant line adjacent said evaporator for expanding refrigerant flowing from said condenser toward said evaporator, air moving means adjacent said evaporator for circulating a stream of air over said evaporator, a drain pan disposed beneath said evaporator for collecting condensate water and frost removed from said evaporator, at least a portion of said drain pan extending into the area between said evaporator and said air moving means, at least a portion of said refrigerant line between said expansion means and said condenser being arranged in said drain pan in said area between said evaporator and said air moving means, a heat conducting cover attached in heat exchange relationship with said refrigerant line and extending over said drain pan between said evaporator and said air moving means to prevent water from being blown out of said drain pan by said air stream flowing thereover and for uniformly distributing heat dissipated by said refrigerant line in said drain pan.

4. A heat pump comprising a reversible cycle refrigeration system including a compressor, an indoor heat exchanger and an outdoor heat exchanger connected in reversible refrigerant flow relationship, a refrigerant line connecting said indoor and outdoor heat exchangers, heating cycle refrigerant expansion means in said refrigerant line adjacent said outdoor heat exchanger for expanding refrigerant flowing from said indoor heat exchanger toward said outdoor heat exchanger, cooling cycle refrigerant expansion means in said refrigerant line adjacent said indoor heat exchanger for expanding refrigerant flowing from said outdoor heat exchanger toward said indoor heat exchanger, air moving means adjacent said outdoor heat exchanger for circulating a stream of outdoor air over said outdoor heat exchanger, a drain pan disposed beneath said outdoor heat exchanger for collecting condensate water and frost removed from said outdoor heat exchanger, at 1e 1st a portion of said drain pan extending mto said area between said outdoor heat exchanger and said air moving means, said refrigerant line having at least a portion thereof between said heating and cooling cycle expansion means arranged in said drain pan in said area between said outdoor heat exchange means and said air moving means, a cover of heat conducting material attached to said refrigerant line and covering said drain pan between said heat exchanger and said air moving means to prevent water in said drain pan from becoming entrained in said air stream flowing thereover and for conducting heat dissipated by said refrigerant line throughout said drain pan.

References Cited in the file of this patent UNITED STATES PATENTS 2,289,035 Neeson July 7, 1942 2,941,381 Eberhart June 21, 1960 2,955,439 Pinter Oct. 11, 1960 

1. A HEAT PUMP COMPRISING A REVERSIBLE REFRIGERATION SYSTEM INCLUDING AN INDOOR HEAT EXCHANGER, AN OUTDOOR HEAT EXCHANGER, A COMPRESSOR, A REFRIGERANT LINE CONNECTING SAID INDOOR AND SAID OUTDOOR HEAT EXCHANGERS, A HEATING CYCLE REFRIGERANT EXPANSION MEANS IN SAID REFRIGERANT LINE FOR EXPANDING REFRIGERANT FLOWING FROM SAID INDOOR HEAT EXCHANGER TOWARD SAID OUTDOOR HEAT EXCHANGER, A COOLING CYCLE REFRIGERANT EXPANSION MEANS IN SAID REFRIGERANT LINE FOR EXPANDING REFRIGERANT FLOWING FROM SAID OUTDOOR HEAT EXCHANGER TOWARD SAID INDOOR HEAT EXCHANGER, A DRAIN PAN ASSOCIATED WITH SAID OUTDOOR HEAT EXCHANGER FOR COLLECTING CONDENSATE WATER AND FROST REMOVED FROM SAID OUTDOOR HEAT EXCHANGER, SAID REFRIGERANT LINE HAVING AT LEAST A PORTION THEREOF BETWEEN SAID HEATING AND COOLING CYCLE EXPANSION MEANS ARRANGED IN HEAT EXCHANGE RELATIONSHIP IN SAID DRAIN PAN FOR WARMING SAID DRAIN PAN AT ALL TIMES DURING FLOW OF REFRIGERANT THROUGH SAID REFRIGERANT LINE, AND A COVER EXTENDING OVER SAID DRAIN PAN ABOVE SAID REFRIGERANT LINE FOR RETAINING WATER COLLECTING WITHIN SAID DRAIN PAN, SAID COVER BEING FORMED OF HEAT CONDUCTING MATERIAL AND IN CONTACT WITH SAID REFRIGERANT LINE SO THAT HEAT DISSIPATED BY SAID REFRIGERANT LINE IS DISTRIBUTED THROUGHOUT SAID DRAIN PAN. 